/*
** $Id: lfunc.c,v 2.30 2012/10/03 12:36:46 roberto Exp $
** Auxiliary functions to manipulate prototypes and closures
** See Copyright Notice in lua.h
*/


#include <stddef.h>

#define lfunc_c
#define LUA_CORE

#include "lua.h"

#include "lfunc.h"
#include "lgc.h"
#include "lmem.h"
#include "lobject.h"
#include "lstate.h"



Closure *luaF_newCclosure (lua_State *L, int n) {
	Closure *c = &luaC_newobj(L, LUA_TCCL, sizeCclosure(n), NULL, 0)->cl;
	c->c.nupvalues = cast_byte(n);
	return c;
}


Closure *luaF_newLclosure (lua_State *L, int n) {
	Closure *c = &luaC_newobj(L, LUA_TLCL, sizeLclosure(n), NULL, 0)->cl;
	c->l.p = NULL;
	c->l.nupvalues = cast_byte(n);
	while (n--) c->l.upvals[n] = NULL;
	return c;
}


UpVal *luaF_newupval (lua_State *L) {
	UpVal *uv = &luaC_newobj(L, LUA_TUPVAL, sizeof(UpVal), NULL, 0)->uv;
	uv->v = &uv->u.value;
	setnilvalue(uv->v);
	return uv;
}


UpVal *luaF_findupval (lua_State *L, StkId level) {
	global_State *g = G(L);
	GCObject **pp = &L->openupval;
	UpVal *p;
	UpVal *uv;
	while (*pp != NULL && (p = gco2uv(*pp))->v >= level) {
		GCObject *o = obj2gco(p);
		lua_assert(p->v != &p->u.value);
		lua_assert(!isold(o) || isold(obj2gco(L)));
		if (p->v == level) {  /* found a corresponding upvalue? */
			if (isdead(g, o))  /* is it dead? */
				changewhite(o);  /* resurrect it */
			return p;
		}
		pp = &p->next;
	}
	/* not found: create a new one */
	uv = &luaC_newobj(L, LUA_TUPVAL, sizeof(UpVal), pp, 0)->uv;
	uv->v = level;  /* current value lives in the stack */
	uv->u.l.prev = &g->uvhead;  /* double link it in `uvhead' list */
	uv->u.l.next = g->uvhead.u.l.next;
	uv->u.l.next->u.l.prev = uv;
	g->uvhead.u.l.next = uv;
	lua_assert(uv->u.l.next->u.l.prev == uv && uv->u.l.prev->u.l.next == uv);
	return uv;
}


static void unlinkupval (UpVal *uv) {
	lua_assert(uv->u.l.next->u.l.prev == uv && uv->u.l.prev->u.l.next == uv);
	uv->u.l.next->u.l.prev = uv->u.l.prev;  /* remove from `uvhead' list */
	uv->u.l.prev->u.l.next = uv->u.l.next;
}


void luaF_freeupval (lua_State *L, UpVal *uv) {
	if (uv->v != &uv->u.value)  /* is it open? */
		unlinkupval(uv);  /* remove from open list */
	luaM_free(L, uv);  /* free upvalue */
}


void luaF_close (lua_State *L, StkId level) {
	UpVal *uv;
	global_State *g = G(L);
	while (L->openupval != NULL && (uv = gco2uv(L->openupval))->v >= level) {
		GCObject *o = obj2gco(uv);
		lua_assert(!isblack(o) && uv->v != &uv->u.value);
		L->openupval = uv->next;  /* remove from `open' list */
		if (isdead(g, o))
			luaF_freeupval(L, uv);  /* free upvalue */
		else {
			unlinkupval(uv);  /* remove upvalue from 'uvhead' list */
			setobj(L, &uv->u.value, uv->v);  /* move value to upvalue slot */
			uv->v = &uv->u.value;  /* now current value lives here */
			gch(o)->next = g->allgc;  /* link upvalue into 'allgc' list */
			g->allgc = o;
			luaC_checkupvalcolor(g, uv);
		}
	}
}


Proto *luaF_newproto (lua_State *L) {
	Proto *f = &luaC_newobj(L, LUA_TPROTO, sizeof(Proto), NULL, 0)->p;
	f->k = NULL;
	f->sizek = 0;
	f->p = NULL;
	f->sizep = 0;
	f->code = NULL;
	f->cache = NULL;
	f->sizecode = 0;
	f->lineinfo = NULL;
	f->sizelineinfo = 0;
	f->upvalues = NULL;
	f->sizeupvalues = 0;
	f->numparams = 0;
	f->is_vararg = 0;
	f->maxstacksize = 0;
	f->locvars = NULL;
	f->sizelocvars = 0;
	f->linedefined = 0;
	f->lastlinedefined = 0;
	f->source = NULL;
	return f;
}


void luaF_freeproto (lua_State *L, Proto *f) {
	luaM_freearray(L, f->code, f->sizecode);
	luaM_freearray(L, f->p, f->sizep);
	luaM_freearray(L, f->k, f->sizek);
	luaM_freearray(L, f->lineinfo, f->sizelineinfo);
	luaM_freearray(L, f->locvars, f->sizelocvars);
	luaM_freearray(L, f->upvalues, f->sizeupvalues);
	luaM_free(L, f);
}


/*
** Look for n-th local variable at line `line' in function `func'.
** Returns NULL if not found.
*/
const char *luaF_getlocalname (const Proto *f, int local_number, int pc) {
	int i;
	for (i = 0; i<f->sizelocvars && f->locvars[i].startpc <= pc; i++) {
		if (pc < f->locvars[i].endpc) {  /* is variable active? */
			local_number--;
			if (local_number == 0)
				return getstr(f->locvars[i].varname);
		}
	}
	return NULL;  /* not found */
}

